High explosives and exploding devices are employed in a wide variety of commercial applications, for example, in mining, in hydrocarbon production, in building demolition, and in other applications. A high explosive may be categorized as either a primary explosive or a secondary explosive. Primary explosives are highly sensitive to stimuli such as impact, friction, heat, and/or electrostatic charges; secondary explosives are less sensitive to stimuli. Those skilled in the art often use the sensitivity of PETN (Pentaerythritol Tetranitrate) explosive as a benchmark. Primary explosives may be identified as explosives that are more sensitive than PETN, and secondary explosives may be identified as explosives that are less sensitive than PETN. Explosives may be additionally characterized by a variety of different parameters including sensitivity to impact, thermal stability, ability to dent a standard metal plate when detonated, crystal size, shape, and other parameters.
Explosives may take a variety of forms including liquids, gels, plastics, and powders. Explosive powders may be compressed to form dense pellets and/or shaped explosive charges. Explosives may comprise percentages of other non-explosive materials, for example, sawdust, powdered silica, diatomaceous earth, plastics, polymers, waxes, and other non-explosive materials. These additional non-explosive materials may contribute to stabilizing an otherwise overly sensitive explosive. The additional non-explosive materials may bind an explosive compound and promote ease of shaping a quantity of the explosive.
High explosives may be said to exhibit two modes of activity—a deflagration mode and a detonation mode. Deflagration may be referred to as a high reaction rate combustion, although the rate is subsonic compared to the speed of sound in the explosive. Detonation may be referred to as a very high reaction rate explosion. During detonation, the reaction propagates through the explosive material in excess of the speed of sound of the subject explosive material. Primary explosives generally may transition substantially immediately to detonation mode upon activation, that is, they have very short run-up distances to detonation. Secondary explosives may first activate in the deflagration mode and may later transition to the detonation mode. In secondary explosives, the run-up distance to detonation is generally longer than for primary explosives.
Commercial applications of high explosives are subject to many regulations and practical constraints. Some high explosives may be subject to United States export restrictions that forbid or limit those nations to which a device employing the high explosive may be shipped. Some high explosives may be subject to United States Department of Transportation (DOT) regulations that forbid or limit the transportation of devices employing the high explosive over public roadways, over public waterways, and/or via common carrier commercial airline flights. Businesses that use high explosives may be constrained by their commercial insurance policies and by the advice of legal counsel with reference to managing liabilities. Not least, prudent considerations for providing safe working conditions constrains the manner of using high explosives and the design of devices incorporating high explosives.